80 THE WHEEL AND AXLE. 



nected cylinders, moveable about a common axis. Such 

 a combination, consisting of 3 wooden cylinders of 6, 4, 

 and 2 cm diameter, moveable round an axis of metal, may 

 be inserted into the frame used for the experiments on 

 falling bodies, as shown in Fig. 54. A small pin, as 

 seen at a, is fixed at any point of the circumference, 

 and a cord is fastened to it. A weight 6r, attached to 

 the end of a cord wound round the smallest cylinder, 

 may be raised by pulling a cord which passes in an 

 opposite direction round one of the larger cylinders. 

 When G rises, a greater length of cord will clearly be 



FIG. 54 (an. proj. not. size). 



wound off the larger cylinder (usually called the wheel) 

 than is wrapped round the smaller cylinder (usually 

 called the axle) ; in the case represented in the figure, 

 the wheel is three times as great as the axle, and hence 

 the length of cord unwrapped will be three times as great 

 as the length wrapped on. If G weighs O kgr '3, and it 

 is required to raise it O m *l, the work necessary is 

 0-3 x 0-1 = 0-03 kilogrammetres. If we pull the cord 

 /, of which O m '3 will have to be wound off, we shall have 



